Castor oil's prized secret now revealed

Mar 18, 2006

Castor plants, source of one of the world's best industrial oils, are gradually revealing the secrets of how they make this prized substance. Scientists with the Agricultural Research Service (ARS) in Albany, Calif., are delving into the mostly-mysterious mechanisms.

Castor oil is unique and is valued as a lubricant for heavy machinery, or for making greases, pharmaceuticals, paints and more.

The researchers' probing has revealed, for the first time, the starring role that a gene called RcDGAT may play in directing the castor plant to put the oil's most important component, known as ricinoleate, into it.

Ricinoleate is safe and free of ricin, the castor bean plants' natural toxin. The word “ricin” in the name “ricinoleate” stems from the plant's scientific name, Ricinus communis.

ARS research chemist Thomas A. McKeon did the work at the ARS Western Regional Research Center in Albany along with research chemist Jiann-Tsyh Lin and ARS research associate and molecular biologist Xiaohua He.

The scientists filed a patent application for the gene last year. Right now, the researchers are continuing to slip the newly identified gene into yeasts in laboratory experiments that will determine more about how to harness RcDGAT's oil-making prowess.

The idea of producing castor's superior oil in some other plant — one that's safe and easy to grow in the United States — isn't new. But RcDGAT will likely be more important in performing that biochemical feat than other castor-plant genes.

The United States imports about $50 million worth of castor oil every year, primarily from India and mainly for industrial uses.

Dow Chemical Co. of Midland, Mich., provided some of the funding through a research and development agreement with ARS, the U.S. Department of Agriculture's chief scientific research agency.